Relocating storage unit data in response to detecting hotspots in a dispersed storage network

ABSTRACT

A method for execution by a dispersed storage and task (DST) processing unit that includes a processor includes generating storage unit heat data based on a plurality of temperature readings received from each of a plurality of storage units, where the storage unit heat data indicates a first hot storage unit. A pair of storage units is selected from the plurality of storage units based on the storage unit heat data, where the pair of storage units includes the first hot storage unit and a second storage unit. A data swap request is generated for transmission to the pair of storage units, where the data swap request includes an instruction to transfer at least one first data slice from the first hot storage unit to the second storage unit and to transfer at least one second data slice from the second storage unit to the first hot storage unit.

CROSS-REFERENCE TO RELATED APPLICATIONS

The present U.S. Utility Patent Application claims priority pursuant to35 U.S.C. § 120 as a continuation of U.S. Utility application Ser. No.15/193,940 entitled “RELOCATING STORAGE UNIT DATA IN RESPONSE TODETECTING HOTSPOTS IN A DISPERSED STORAGE NETWORK”, filed Jun. 27, 2016,which is hereby incorporated herein by reference in its entirety andmade part of the present U.S. Utility Patent Application for allpurposes.

STATEMENT REGARDING FEDERALLY SPONSORED RESEARCH OR DEVELOPMENT

Not applicable.

INCORPORATION-BY-REFERENCE OF MATERIAL SUBMITTED ON A COMPACT DISC

Not applicable.

BACKGROUND OF THE INVENTION Technical Field of the Invention

This invention relates generally to computer networks and moreparticularly to dispersing error encoded data.

Description of Related Art

Computing devices are known to communicate data, process data, and/orstore data. Such computing devices range from wireless smart phones,laptops, tablets, personal computers (PC), work stations, and video gamedevices, to data centers that support millions of web searches, stocktrades, or on-line purchases every day. In general, a computing deviceincludes a central processing unit (CPU), a memory system, userinput/output interfaces, peripheral device interfaces, and aninterconnecting bus structure.

As is further known, a computer may effectively extend its CPU by using“cloud computing” to perform one or more computing functions (e.g., aservice, an application, an algorithm, an arithmetic logic function,etc.) on behalf of the computer. Further, for large services,applications, and/or functions, cloud computing may be performed bymultiple cloud computing resources in a distributed manner to improvethe response time for completion of the service, application, and/orfunction. For example, Hadoop is an open source software framework thatsupports distributed applications enabling application execution bythousands of computers.

In addition to cloud computing, a computer may use “cloud storage” aspart of its memory system. As is known, cloud storage enables a user,via its computer, to store files, applications, etc. on an Internetstorage system. The Internet storage system may include a RAID(redundant array of independent disks) system and/or a dispersed storagesystem that uses an error correction scheme to encode data for storage.

BRIEF DESCRIPTION OF THE SEVERAL VIEWS OF THE DRAWING(S)

FIG. 1 is a schematic block diagram of an embodiment of a dispersed ordistributed storage network (DSN) in accordance with the presentinvention;

FIG. 2 is a schematic block diagram of an embodiment of a computing corein accordance with the present invention;

FIG. 3 is a schematic block diagram of an example of dispersed storageerror encoding of data in accordance with the present invention;

FIG. 4 is a schematic block diagram of a generic example of an errorencoding function in accordance with the present invention;

FIG. 5 is a schematic block diagram of a specific example of an errorencoding function in accordance with the present invention;

FIG. 6 is a schematic block diagram of an example of a slice name of anencoded data slice (EDS) in accordance with the present invention;

FIG. 7 is a schematic block diagram of an example of dispersed storageerror decoding of data in accordance with the present invention;

FIG. 8 is a schematic block diagram of a generic example of an errordecoding function in accordance with the present invention;

FIG. 9 is a schematic block diagram of an embodiment of a dispersed ordistributed storage network (DSN) in accordance with the presentinvention; and

FIG. 10 is a logic diagram of an example of a method of relocatingstorage unit data in response to detecting hotspots in accordance withthe present invention.

DETAILED DESCRIPTION OF THE INVENTION

FIG. 1 is a schematic block diagram of an embodiment of a dispersed, ordistributed, storage network (DSN) 10 that includes a plurality ofcomputing devices 12-16, a managing unit 18, an integrity processingunit 20, and a DSN memory 22. The components of the DSN 10 are coupledto a network 24, which may include one or more wireless and/or wirelined communication systems; one or more non-public intranet systemsand/or public interne systems; and/or one or more local area networks(LAN) and/or wide area networks (WAN).

The DSN memory 22 includes a plurality of storage units 36 that may belocated at geographically different sites (e.g., one in Chicago, one inMilwaukee, etc.), at a common site, or a combination thereof. Forexample, if the DSN memory 22 includes eight storage units 36, eachstorage unit is located at a different site. As another example, if theDSN memory 22 includes eight storage units 36, all eight storage unitsare located at the same site. As yet another example, if the DSN memory22 includes eight storage units 36, a first pair of storage units are ata first common site, a second pair of storage units are at a secondcommon site, a third pair of storage units are at a third common site,and a fourth pair of storage units are at a fourth common site. Notethat a DSN memory 22 may include more or less than eight storage units36. Further note that each storage unit 36 includes a computing core (asshown in FIG. 2, or components thereof) and a plurality of memorydevices for storing dispersed error encoded data.

Each of the computing devices 12-16, the managing unit 18, and theintegrity processing unit 20 include a computing core 26, which includesnetwork interfaces 30-33. Computing devices 12-16 may each be a portablecomputing device and/or a fixed computing device. A portable computingdevice may be a social networking device, a gaming device, a cell phone,a smart phone, a digital assistant, a digital music player, a digitalvideo player, a laptop computer, a handheld computer, a tablet, a videogame controller, and/or any other portable device that includes acomputing core. A fixed computing device may be a computer (PC), acomputer server, a cable set-top box, a satellite receiver, a televisionset, a printer, a fax machine, home entertainment equipment, a videogame console, and/or any type of home or office computing equipment.Note that each of the managing unit 18 and the integrity processing unit20 may be separate computing devices, may be a common computing device,and/or may be integrated into one or more of the computing devices 12-16and/or into one or more of the storage units 36.

Each interface 30, 32, and 33 includes software and hardware to supportone or more communication links via the network 24 indirectly and/ordirectly. For example, interface 30 supports a communication link (e.g.,wired, wireless, direct, via a LAN, via the network 24, etc.) betweencomputing devices 14 and 16. As another example, interface 32 supportscommunication links (e.g., a wired connection, a wireless connection, aLAN connection, and/or any other type of connection to/from the network24) between computing devices 12 & 16 and the DSN memory 22. As yetanother example, interface 33 supports a communication link for each ofthe managing unit 18 and the integrity processing unit 20 to the network24.

Computing devices 12 and 16 include a dispersed storage (DS) clientmodule 34, which enables the computing device to dispersed storage errorencode and decode data as subsequently described with reference to oneor more of FIGS. 3-8. In this example embodiment, computing device 16functions as a dispersed storage processing agent for computing device14. In this role, computing device 16 dispersed storage error encodesand decodes data on behalf of computing device 14. With the use ofdispersed storage error encoding and decoding, the DSN 10 is tolerant ofa significant number of storage unit failures (the number of failures isbased on parameters of the dispersed storage error encoding function)without loss of data and without the need for a redundant or backupcopies of the data. Further, the DSN 10 stores data for an indefiniteperiod of time without data loss and in a secure manner (e.g., thesystem is very resistant to unauthorized attempts at accessing thedata).

In operation, the managing unit 18 performs DS management services. Forexample, the managing unit 18 establishes distributed data storageparameters (e.g., vault creation, distributed storage parameters,security parameters, billing information, user profile information,etc.) for computing devices 12-14 individually or as part of a group ofuser devices. As a specific example, the managing unit 18 coordinatescreation of a vault (e.g., a virtual memory block associated with aportion of an overall namespace of the DSN) within the DSTN memory 22for a user device, a group of devices, or for public access andestablishes per vault dispersed storage (DS) error encoding parametersfor a vault. The managing unit 18 facilitates storage of DS errorencoding parameters for each vault by updating registry information ofthe DSN 10, where the registry information may be stored in the DSNmemory 22, a computing device 12-16, the managing unit 18, and/or theintegrity processing unit 20.

The DSN managing unit 18 creates and stores user profile information(e.g., an access control list (ACL)) in local memory and/or withinmemory of the DSN memory 22. The user profile information includesauthentication information, permissions, and/or the security parameters.The security parameters may include encryption/decryption scheme, one ormore encryption keys, key generation scheme, and/or dataencoding/decoding scheme.

The DSN managing unit 18 creates billing information for a particularuser, a user group, a vault access, public vault access, etc. Forinstance, the DSTN managing unit 18 tracks the number of times a useraccesses a non-public vault and/or public vaults, which can be used togenerate a per-access billing information. In another instance, the DSTNmanaging unit 18 tracks the amount of data stored and/or retrieved by auser device and/or a user group, which can be used to generate aper-data-amount billing information.

As another example, the managing unit 18 performs network operations,network administration, and/or network maintenance. Network operationsincludes authenticating user data allocation requests (e.g., read and/orwrite requests), managing creation of vaults, establishingauthentication credentials for user devices, adding/deleting components(e.g., user devices, storage units, and/or computing devices with a DSclient module 34) to/from the DSN 10, and/or establishing authenticationcredentials for the storage units 36. Network administration includesmonitoring devices and/or units for failures, maintaining vaultinformation, determining device and/or unit activation status,determining device and/or unit loading, and/or determining any othersystem level operation that affects the performance level of the DSN 10.Network maintenance includes facilitating replacing, upgrading,repairing, and/or expanding a device and/or unit of the DSN 10.

The integrity processing unit 20 performs rebuilding of ‘bad’ or missingencoded data slices. At a high level, the integrity processing unit 20performs rebuilding by periodically attempting to retrieve/list encodeddata slices, and/or slice names of the encoded data slices, from the DSNmemory 22. For retrieved encoded slices, they are checked for errors dueto data corruption, outdated version, etc. If a slice includes an error,it is flagged as a ‘bad’ slice. For encoded data slices that were notreceived and/or not listed, they are flagged as missing slices. Badand/or missing slices are subsequently rebuilt using other retrievedencoded data slices that are deemed to be good slices to produce rebuiltslices. The rebuilt slices are stored in the DSTN memory 22.

FIG. 2 is a schematic block diagram of an embodiment of a computing core26 that includes a processing module 50, a memory controller 52, mainmemory 54, a video graphics processing unit 55, an input/output (IO)controller 56, a peripheral component interconnect (PCI) interface 58,an IO interface module 60, at least one IO device interface module 62, aread only memory (ROM) basic input output system (BIOS) 64, and one ormore memory interface modules. The one or more memory interfacemodule(s) includes one or more of a universal serial bus (USB) interfacemodule 66, a host bus adapter (HBA) interface module 68, a networkinterface module 70, a flash interface module 72, a hard drive interfacemodule 74, and a DSN interface module 76.

The DSN interface module 76 functions to mimic a conventional operatingsystem (OS) file system interface (e.g., network file system (NFS),flash file system (FFS), disk file system (DFS), file transfer protocol(FTP), web-based distributed authoring and versioning (WebDAV), etc.)and/or a block memory interface (e.g., small computer system interface(SCSI), internet small computer system interface (iSCSI), etc.). The DSNinterface module 76 and/or the network interface module 70 may functionas one or more of the interface 30-33 of FIG. 1. Note that the IO deviceinterface module 62 and/or the memory interface modules 66-76 may becollectively or individually referred to as IO ports.

FIG. 3 is a schematic block diagram of an example of dispersed storageerror encoding of data. When a computing device 12 or 16 has data tostore it disperse storage error encodes the data in accordance with adispersed storage error encoding process based on dispersed storageerror encoding parameters. The dispersed storage error encodingparameters include an encoding function (e.g., information dispersalalgorithm, Reed-Solomon, Cauchy Reed-Solomon, systematic encoding,non-systematic encoding, on-line codes, etc.), a data segmentingprotocol (e.g., data segment size, fixed, variable, etc.), and per datasegment encoding values. The per data segment encoding values include atotal, or pillar width, number (T) of encoded data slices per encodingof a data segment i.e., in a set of encoded data slices); a decodethreshold number (D) of encoded data slices of a set of encoded dataslices that are needed to recover the data segment; a read thresholdnumber (R) of encoded data slices to indicate a number of encoded dataslices per set to be read from storage for decoding of the data segment;and/or a write threshold number (W) to indicate a number of encoded dataslices per set that must be accurately stored before the encoded datasegment is deemed to have been properly stored. The dispersed storageerror encoding parameters may further include slicing information (e.g.,the number of encoded data slices that will be created for each datasegment) and/or slice security information (e.g., per encoded data sliceencryption, compression, integrity checksum, etc.).

In the present example, Cauchy Reed-Solomon has been selected as theencoding function (a generic example is shown in FIG. 4 and a specificexample is shown in FIG. 5); the data segmenting protocol is to dividethe data object into fixed sized data segments; and the per data segmentencoding values include: a pillar width of 5, a decode threshold of 3, aread threshold of 4, and a write threshold of 4. In accordance with thedata segmenting protocol, the computing device 12 or 16 divides the data(e.g., a file (e.g., text, video, audio, etc.), a data object, or otherdata arrangement) into a plurality of fixed sized data segments (e.g., 1through Y of a fixed size in range of Kilo-bytes to Tera-bytes or more).The number of data segments created is dependent of the size of the dataand the data segmenting protocol.

The computing device 12 or 16 then disperse storage error encodes a datasegment using the selected encoding function (e.g., Cauchy Reed-Solomon)to produce a set of encoded data slices. FIG. 4 illustrates a genericCauchy Reed-Solomon encoding function, which includes an encoding matrix(EM), a data matrix (DM), and a coded matrix (CM). The size of theencoding matrix (EM) is dependent on the pillar width number (T) and thedecode threshold number (D) of selected per data segment encodingvalues. To produce the data matrix (DM), the data segment is dividedinto a plurality of data blocks and the data blocks are arranged into Dnumber of rows with Z data blocks per row. Note that Z is a function ofthe number of data blocks created from the data segment and the decodethreshold number (D). The coded matrix is produced by matrix multiplyingthe data matrix by the encoding matrix.

FIG. 5 illustrates a specific example of Cauchy Reed-Solomon encodingwith a pillar number (T) of five and decode threshold number of three.In this example, a first data segment is divided into twelve data blocks(D1-D12). The coded matrix includes five rows of coded data blocks,where the first row of X11-X14 corresponds to a first encoded data slice(EDS 1_1), the second row of X21-X24 corresponds to a second encodeddata slice (EDS 2_1), the third row of X31-X34 corresponds to a thirdencoded data slice (EDS 3_1), the fourth row of X41-X44 corresponds to afourth encoded data slice (EDS 4_1), and the fifth row of X51-X54corresponds to a fifth encoded data slice (EDS 5_1). Note that thesecond number of the EDS designation corresponds to the data segmentnumber.

Returning to the discussion of FIG. 3, the computing device also createsa slice name (SN) for each encoded data slice (EDS) in the set ofencoded data slices. A typical format for a slice name 60 is shown inFIG. 6. As shown, the slice name (SN) 60 includes a pillar number of theencoded data slice (e.g., one of 1-T), a data segment number (e.g., oneof 1-Y), a vault identifier (ID), a data object identifier (ID), and mayfurther include revision level information of the encoded data slices.The slice name functions as, at least part of, a DSN address for theencoded data slice for storage and retrieval from the DSN memory 22.

As a result of encoding, the computing device 12 or 16 produces aplurality of sets of encoded data slices, which are provided with theirrespective slice names to the storage units for storage. As shown, thefirst set of encoded data slices includes EDS 1_1 through EDS 5_1 andthe first set of slice names includes SN 1_1 through SN 5_1 and the lastset of encoded data slices includes EDS 1_Y through EDS 5_Y and the lastset of slice names includes SN 1_Y through SN 5_Y.

FIG. 7 is a schematic block diagram of an example of dispersed storageerror decoding of a data object that was dispersed storage error encodedand stored in the example of FIG. 4. In this example, the computingdevice 12 or 16 retrieves from the storage units at least the decodethreshold number of encoded data slices per data segment. As a specificexample, the computing device retrieves a read threshold number ofencoded data slices.

To recover a data segment from a decode threshold number of encoded dataslices, the computing device uses a decoding function as shown in FIG.8. As shown, the decoding function is essentially an inverse of theencoding function of FIG. 4. The coded matrix includes a decodethreshold number of rows (e.g., three in this example) and the decodingmatrix in an inversion of the encoding matrix that includes thecorresponding rows of the coded matrix. For example, if the coded matrixincludes rows 1, 2, and 4, the encoding matrix is reduced to rows 1, 2,and 4, and then inverted to produce the decoding matrix.

FIG. 9 is a schematic block diagram of another embodiment of a dispersedstorage network (DSN) that includes a distributed storage and task (DST)processing unit 16 of FIG. 1, the network 24 of FIG. 1, and a pluralityof DST execution (EX) units 1-n. Each DST processing unit 16 can includethe interface 32 of FIG. 1, the computing core 26 of FIG. 1, and the DSTclient module 34 of FIG. 1. Each DST execution unit includes the DSTclient module 34 of FIG. 1, and can include a temperature sensor 910.Hereafter, each DST execution unit may be interchangeably referred to asa storage unit. Each DST execution unit may be implemented utilizing theDST execution unit 36 of FIG. 1. The DSN functions to relocate storageunit data in response to detecting hotspots.

Running at higher levels of heat often corresponds to higher rates ofcomponent failure. Data centers often contain hotspots, corresponding tophysical locations and/or physical devices that tend to have a highertemperature. Hotspots can occur even in data centers that arewell-designed and well-ventilated. For example, hotspots can occur onthe top level of a rack compared to a middle or bottom level. Hotspotscan also occur due to proximity to devices that are highly used.Hotspots can even cause equivalent devices to vary significantly ininternal temperature.

In various embodiments, reliability can be maximized in a DSN byswapping storage location of data based on the occurrence of hotspots.In various embodiments, slices stored in two or more storage units,entire vaults between storage units, and/or the entirety of data storedin two or more storage units can be swapped in response to detectinghotspots. For example, a DST processing unit can receive temperaturedata from the storage units in the DSN. Historical temperature over timefor storage units in the DSN can be used to determine an average and/orexpected temperature for each storage unit. The temperature data of astorage unit over time can be adjusted for levels of activity of thatstorage unit. For example, a DST processing unit can receive currenttemperature readings periodically from the storage units in the DSN, andcan keep a record of past temperature readings and/or averagetemperature readings. Past temperature readings can be stored, forexample, in a memory of the DST processing unit, such as memory 54 ofFIG. 2. Hot storage units that are subject to significantly increasedrates of failure or memory device failure can be identified, forexample, by virtue of running hotter than other storage units and/or byvirtue of running hotter than the historical average for that particularstorage unit. Some or all of the data of these hot storage units can berelocated to cooler storage units to increase reliability of the system.For example, hot storage units can be paired with units of equivalent ornear equivalent storage capacity that are running at safer, average,and/or cooler temperatures. Some or all of the data stored in each pairof storage units can be swapped accordingly. This virtual swap caninclude relocating slice data, identity, credentials, etc. from the coolstorage unit to the hot storage unit and vice versa. For example, a DSTprocessing unit can send requests to move some or all of the data fromthe hot storage unit to the cool storage unit and to move some or all ofthe data from the cool storage unit to the hot storage unit. In variousembodiments, where there isn't enough storage between the two storageunits to facilitate this swap directly, a third storage unit can bedesignated to temporarily store data of one storage unit to facilitatethe swap. In similar embodiments, temporary storage to facilitate theswap can instead be distributed over multiple storage units withavailable space. In various embodiments, memory of the DST processingunit itself can be designated to temporarily store data to facilitatethe swap.

In various embodiments, selecting the pairs of storage units involved inthese swaps can be based on minimizing the number of hot storage unitswithin any single “stripe” of storage units, where a stripe of storageunits corresponds to a set of storage units that store data slicescorresponding to the same data object, the same set of data objects,and/or the same data source. One or more storage units that are in sucha stripe of storage units can be paired with storage units that are notin the stripe. In various embodiments, this strategy may be employed tokeep the number of hot storage units in a stripe below a certain countor ratio. In various embodiments, a DST processing unit can determine aplurality of stripes, where each of the plurality of stripes correspondssets of storage units storing data slices corresponding to the same dataobject, same set of data objects, and/or same data source. From this,the DST processing unit can determine a plurality of “high risk” stripeswhich correspond to stripes that are above the threshold and/or stripesthat have the highest hot storage unit count or ratio, and choose toswap hot storage units of these high risk stripes. In variousembodiments, the DST processing unit can also determine hot storageunits that are members of multiple high-risk stripes, and furtherprioritize that hot storage units that are members of a greater numberof high risk stripes be included in pairs to be swapped.

In various embodiments, selecting pairs of storage units involved inthese swaps can be based on encoding schemes employed by some or all ofthe data slices of a storage unit. For example, the hot storage unitscan be used to serve data slices and/or entire vaults that have higherlevels of fault tolerance and reliability. For example, a pair ofstorage units can be selected based on the fault tolerance level of someor all of the encoded data slices stored by the storage units. Forexample, encoded slices corresponding to a less resilient IDAconfiguration in a hot storage unit can be swapped with encoded slicescorresponding to a more resilient IDA configuration in a cool storageunit. By employing this strategy, the hot storage units can absorb thehigher rates of failure associated with the higher temperature levelswithout putting the data it stores at as high of a risk.

In various embodiments, temperature sensor 910 can include athermometer, a resistance temperature detector, a thermocouple, and/or athermistor. In various embodiments, each storage unit can include asingle temperature sensor or a plurality of temperature sensors. Invarious embodiments, a single temperature sensor can take temperaturereadings for multiple storage units. In various embodiments, storageunits can monitor their own temperature levels, and transmit anotification indicating temperature readings only when the temperaturereadings are high and/or indicate a hotspot. In other embodiments, thestorage units can transmit temperature readings in regular intervalsand/or in response to a request by a DST processing unit.

In various embodiments, the temperature level that deems a storage unit“hot” can be the same or different for the storage units in the DSN. Invarious embodiments, such a threshold for a particular storage unit canbe dependent on average activity of the storage unit, average resilienceof the encoding schemes employed by the data slices stored in thestorage unit, and/or average importance of the data stored at thestorage unit. In various embodiments, the threshold can be variable foreach storage unit based on the current activity level and/or theresilience of data currently stored by the storage unit. In variousembodiments, these parameters can be stored in a memory of the DSTprocessing unit and/or a memory of the storage unit, such as memory 54of FIG. 2.

In various embodiments, a DST processing unit and/or storage unit itselfcan “predict” hotspot behavior. For example, past temperature patternscan be used to correlate higher temperatures of one or more storageunits to the performing certain functions and/or processes. Highertemperatures can also correlate to particular times of day regularlythat may regularly correspond to higher temperatures and/or higheractivity. In various embodiments, if a storage unit is currentlyundergoing or about to undergo an intensive process corresponding to ahigher activity level, this storage unit can be designated as a hotstorage unit, even without a temperature reading, as such higheractivity level is predicted to correlate to higher temperature levels.

In various embodiments, rather than transferring the data from onestorage unit to another, the storage units can be physically swapped. Aphysical swap involves physically moving the cool storage unit to thelocation of the hot storage unit, and the hot storage unit to the formerlocation of the cool storage unit. For example, rather than facilitatingthe data transfer, the DST processing unit can instead transmit anotification indicating one or more pairs of storage units to beswapped. In response, a user associated with the DSN can physically swapthe locations of the hot and cool storage unit in the pair in responseto receiving the notification. In various embodiments where a physicalswap is required, the DSN can select a cool storage unit that is also ina physically convenient location, for example, a cool storage unit thatis adjacent to and/or on the same rack as the hot storage unit,physically close to a user that will facilitate the physical swap,located on a level of the rack that is easy for the user to reach,corresponds to hardware that is easy to carry, etc.

In various embodiments, a processing system of a dispersed storage andtask (DST) processing unit includes at least one processor and a memorythat stores operational instructions, that when executed by the at leastone processor cause the processing system to generate storage unit heatdata based on a plurality of temperature readings received from each ofa plurality of storage units, where the storage unit heat data indicatesa first hot storage unit. A pair of storage units are selected from theplurality of storage units based on the storage unit heat data, wherethe pair of storage units includes the first hot storage unit and asecond storage unit. A data swap request is generated for transmissionto the pair of storage units, where the data swap request includes aninstruction to transfer at least one first data slice from the first hotstorage unit to the second storage unit, and to transfer at least onesecond data slice from the second storage unit to the first hot storageunit.

In various embodiments, generating the storage unit heat data includescomparing each received temperature reading to a heat threshold. Thestorage unit heat data indicates the first hot storage unit in responseto the received temperature reading of the first hot storage unit beingabove the heat threshold. In various embodiments, generating the storageunit heat data includes ranking the received plurality of temperaturereadings, where the first hot storage unit corresponds to a highesttemperature reading of the plurality of temperature readings. In variousembodiments, the received plurality of temperature readings are storedin a memory of the DST processing unit, where generating the storageunit heat data is further based on past temperature readings stored inthe memory. In various embodiments, generating the storage unit heatdata is further based on a plurality of activity levels received fromthe plurality of storage units. In various embodiments, the secondstorage unit is selected in response to the storage unit heat dataindicating that the second storage unit has a normal temperaturereading.

In various embodiments, fault tolerance data is generated based on aplurality of fault tolerance levels corresponding to the plurality ofstorage units, and wherein selecting the pair of storage units isfurther based on the fault tolerance data. In various embodiments, thesecond storage unit is selected in response to the fault tolerance dataindicating that the at least one second data slice from the secondstorage unit is encoded with a higher fault tolerance than the at leastone first data slice from the first hot storage unit.

In various embodiments, slice location data is generated for each of aplurality of data objects, wherein the slice location data for each ofthe plurality of data objects indicates a plurality of memory locationscorresponding to a plurality of data slices of the data object. Each ofthe plurality of memory locations correspond to at least one of theplurality of storage units, and selecting the pair of storage units isfurther based on the slice location data of each of the plurality ofdata objects. In various embodiments, the storage unit heat dataindicates a plurality of hot storage units which includes the first hotstorage unit. The pair of storage units is selected in response to theslice location data indicating that one of the plurality of data objectshas more than a threshold number of data slices stored in hot storageunits, where the at least one first data slice of the first hot storageunit includes a subset of the plurality of data slices of the dataobject.

In various embodiments, the storage unit heat data further indicates asecond hot storage unit. A second pair of storage units is selected fromthe plurality of storage units based on the storage unit heat data,where the pair of storage units includes the second hot storage unit anda fourth storage unit, and where the second hot storage unit is storedin a first physical location, and where the fourth storage unit isstored in a second physical location. A notification is generated fortransmission indicating that the second pair of storage units need to bephysically swapped by moving the second hot storage unit to secondphysical location and by moving the fourth storage unit to the firstphysical location.

FIG. 10 is a flowchart illustrating an example of relocating storageunit data in response to detecting hotspots. In particular, a method ispresented for use in conjunction with one or more functions and featuresdescribed in conjunction with FIGS. 1-9 is presented for execution by adispersed storage and task (DST) processing unit that includes aprocessor or via another processing system of a dispersed storagenetwork that includes at least one processor and memory that storesinstruction that configure the processor or processors to perform thesteps described below. Step 1002 includes generating storage unit heatdata based on a plurality of temperature readings received from each ofa plurality of storage units, where the storage unit heat data indicatesa first hot storage unit. Step 1004 includes selecting a pair of storageunits from the plurality of storage units based on the storage unit heatdata, where the pair of storage units includes the first hot storageunit and a second storage unit. Step 1006 includes generating a dataswap request for transmission to the pair of storage units, where thedata swap request includes an instruction to transfer at least one firstdata slice from the first hot storage unit to the second storage unitand to transfer at least one second data slice from the second storageunit to the first hot storage unit.

In various embodiments, generating the storage unit heat data includescomparing each received temperature reading to a heat threshold. Thestorage unit heat data indicates the first hot storage unit in responseto the received temperature reading of the first hot storage unit beingabove the heat threshold. In various embodiments, generating the storageunit heat data includes ranking the received plurality of temperaturereadings, where the first hot storage unit corresponds to a highesttemperature reading of the plurality of temperature readings. In variousembodiments, the received plurality of temperature readings are storedin a memory of the DST processing unit, where generating the storageunit heat data is further based on past temperature readings stored inthe memory. In various embodiments, generating the storage unit heatdata is further based on a plurality of activity levels received fromthe plurality of storage units. In various embodiments, the secondstorage unit is selected in response to the storage unit heat dataindicating that the second storage unit has a normal temperaturereading.

In various embodiments, fault tolerance data is generated based on aplurality of fault tolerance levels corresponding to the plurality ofstorage units, and wherein selecting the pair of storage units isfurther based on the fault tolerance data. In various embodiments, thesecond storage unit is selected in response to the fault tolerance dataindicating that the at least one second data slice from the secondstorage unit is encoded with a higher fault tolerance than the at leastone first data slice from the first hot storage unit.

In various embodiments, slice location data is generated for each of aplurality of data objects, wherein the slice location data for each ofthe plurality of data objects indicates a plurality of memory locationscorresponding to a plurality of data slices of the data object. Each ofthe plurality of memory locations correspond to at least one of theplurality of storage units, and selecting the pair of storage units isfurther based on the slice location data of each of the plurality ofdata objects. In various embodiments, the storage unit heat dataindicates a plurality of hot storage units which includes the first hotstorage unit. The pair of storage units is selected in response to theslice location data indicating that one of the plurality of data objectshas more than a threshold number of data slices stored in hot storageunits, where the at least one first data slice of the first hot storageunit includes a subset of the plurality of data slices of the dataobject.

In various embodiments, the storage unit heat data further indicates asecond hot storage unit. A second pair of storage units is selected fromthe plurality of storage units based on the storage unit heat data,where the pair of storage units includes the second hot storage unit anda fourth storage unit, and where the second hot storage unit is storedin a first physical location, and where the fourth storage unit isstored in a second physical location. A notification is generated fortransmission indicating that the second pair of storage units need to bephysically swapped by moving the second hot storage unit to secondphysical location and by moving the fourth storage unit to the firstphysical location.

It is noted that terminologies as may be used herein such as bit stream,stream, signal sequence, etc. (or their equivalents) have been usedinterchangeably to describe digital information whose contentcorresponds to any of a number of desired types (e.g., data, video,speech, audio, etc. any of which may generally be referred to as‘data’).

As may be used herein, the terms “substantially” and “approximately”provides an industry-accepted tolerance for its corresponding termand/or relativity between items. Such an industry-accepted toleranceranges from less than one percent to fifty percent and corresponds to,but is not limited to, component values, integrated circuit processvariations, temperature variations, rise and fall times, and/or thermalnoise. Such relativity between items ranges from a difference of a fewpercent to magnitude differences. As may also be used herein, theterm(s) “configured to”, “operably coupled to”, “coupled to”, and/or“coupling” includes direct coupling between items and/or indirectcoupling between items via an intervening item (e.g., an item includes,but is not limited to, a component, an element, a circuit, and/or amodule) where, for an example of indirect coupling, the intervening itemdoes not modify the information of a signal but may adjust its currentlevel, voltage level, and/or power level. As may further be used herein,inferred coupling (i.e., where one element is coupled to another elementby inference) includes direct and indirect coupling between two items inthe same manner as “coupled to”. As may even further be used herein, theterm “configured to”, “operable to”, “coupled to”, or “operably coupledto” indicates that an item includes one or more of power connections,input(s), output(s), etc., to perform, when activated, one or more itscorresponding functions and may further include inferred coupling to oneor more other items. As may still further be used herein, the term“associated with”, includes direct and/or indirect coupling of separateitems and/or one item being embedded within another item.

As may be used herein, the term “compares favorably”, indicates that acomparison between two or more items, signals, etc., provides a desiredrelationship. For example, when the desired relationship is that signal1 has a greater magnitude than signal 2, a favorable comparison may beachieved when the magnitude of signal 1 is greater than that of signal 2or when the magnitude of signal 2 is less than that of signal 1. As maybe used herein, the term “compares unfavorably”, indicates that acomparison between two or more items, signals, etc., fails to providethe desired relationship.

As may also be used herein, the terms “processing module”, “processingcircuit”, “processor”, and/or “processing unit” may be a singleprocessing device or a plurality of processing devices. Such aprocessing device may be a microprocessor, micro-controller, digitalsignal processor, microcomputer, central processing unit, fieldprogrammable gate array, programmable logic device, state machine, logiccircuitry, analog circuitry, digital circuitry, and/or any device thatmanipulates signals (analog and/or digital) based on hard coding of thecircuitry and/or operational instructions. The processing module,module, processing circuit, and/or processing unit may be, or furtherinclude, memory and/or an integrated memory element, which may be asingle memory device, a plurality of memory devices, and/or embeddedcircuitry of another processing module, module, processing circuit,and/or processing unit. Such a memory device may be a read-only memory,random access memory, volatile memory, non-volatile memory, staticmemory, dynamic memory, flash memory, cache memory, and/or any devicethat stores digital information. Note that if the processing module,module, processing circuit, and/or processing unit includes more thanone processing device, the processing devices may be centrally located(e.g., directly coupled together via a wired and/or wireless busstructure) or may be distributedly located (e.g., cloud computing viaindirect coupling via a local area network and/or a wide area network).Further note that if the processing module, module, processing circuit,and/or processing unit implements one or more of its functions via astate machine, analog circuitry, digital circuitry, and/or logiccircuitry, the memory and/or memory element storing the correspondingoperational instructions may be embedded within, or external to, thecircuitry comprising the state machine, analog circuitry, digitalcircuitry, and/or logic circuitry. Still further note that, the memoryelement may store, and the processing module, module, processingcircuit, and/or processing unit executes, hard coded and/or operationalinstructions corresponding to at least some of the steps and/orfunctions illustrated in one or more of the Figures. Such a memorydevice or memory element can be included in an article of manufacture.

One or more embodiments have been described above with the aid of methodsteps illustrating the performance of specified functions andrelationships thereof. The boundaries and sequence of these functionalbuilding blocks and method steps have been arbitrarily defined hereinfor convenience of description. Alternate boundaries and sequences canbe defined so long as the specified functions and relationships areappropriately performed. Any such alternate boundaries or sequences arethus within the scope and spirit of the claims. Further, the boundariesof these functional building blocks have been arbitrarily defined forconvenience of description. Alternate boundaries could be defined aslong as the certain significant functions are appropriately performed.Similarly, flow diagram blocks may also have been arbitrarily definedherein to illustrate certain significant functionality.

To the extent used, the flow diagram block boundaries and sequence couldhave been defined otherwise and still perform the certain significantfunctionality. Such alternate definitions of both functional buildingblocks and flow diagram blocks and sequences are thus within the scopeand spirit of the claims. One of average skill in the art will alsorecognize that the functional building blocks, and other illustrativeblocks, modules and components herein, can be implemented as illustratedor by discrete components, application specific integrated circuits,processors executing appropriate software and the like or anycombination thereof.

In addition, a flow diagram may include a “start” and/or “continue”indication. The “start” and “continue” indications reflect that thesteps presented can optionally be incorporated in or otherwise used inconjunction with other routines. In this context, “start” indicates thebeginning of the first step presented and may be preceded by otheractivities not specifically shown. Further, the “continue” indicationreflects that the steps presented may be performed multiple times and/ormay be succeeded by other activities not specifically shown. Further,while a flow diagram indicates a particular ordering of steps, otherorderings are likewise possible provided that the principles ofcausality are maintained.

The one or more embodiments are used herein to illustrate one or moreaspects, one or more features, one or more concepts, and/or one or moreexamples. A physical embodiment of an apparatus, an article ofmanufacture, a machine, and/or of a process may include one or more ofthe aspects, features, concepts, examples, etc. described with referenceto one or more of the embodiments discussed herein. Further, from figureto figure, the embodiments may incorporate the same or similarly namedfunctions, steps, modules, etc. that may use the same or differentreference numbers and, as such, the functions, steps, modules, etc. maybe the same or similar functions, steps, modules, etc. or differentones.

Unless specifically stated to the contra, signals to, from, and/orbetween elements in a figure of any of the figures presented herein maybe analog or digital, continuous time or discrete time, and single-endedor differential. For instance, if a signal path is shown as asingle-ended path, it also represents a differential signal path.Similarly, if a signal path is shown as a differential path, it alsorepresents a single-ended signal path. While one or more particulararchitectures are described herein, other architectures can likewise beimplemented that use one or more data buses not expressly shown, directconnectivity between elements, and/or indirect coupling between otherelements as recognized by one of average skill in the art.

The term “module” is used in the description of one or more of theembodiments. A module implements one or more functions via a device suchas a processor or other processing device or other hardware that mayinclude or operate in association with a memory that stores operationalinstructions. A module may operate independently and/or in conjunctionwith software and/or firmware. As also used herein, a module may containone or more sub-modules, each of which may be one or more modules.

As may further be used herein, a computer readable memory includes oneor more memory elements. A memory element may be a separate memorydevice, multiple memory devices, or a set of memory locations within amemory device. Such a memory device may be a read-only memory, randomaccess memory, volatile memory, non-volatile memory, static memory,dynamic memory, flash memory, cache memory, and/or any device thatstores digital information. The memory device may be in a form a solidstate memory, a hard drive memory, cloud memory, thumb drive, servermemory, computing device memory, and/or other physical medium forstoring digital information.

While particular combinations of various functions and features of theone or more embodiments have been expressly described herein, othercombinations of these features and functions are likewise possible. Thepresent disclosure is not limited by the particular examples disclosedherein and expressly incorporates these other combinations.

What is claimed is:
 1. A method for execution by a processing system ofa dispersed storage network (DSN) that includes a processor, the methodcomprises: determining one or more slice names of one or more encodeddata slices, wherein one or more data segments of data are dispersedstorage error encoded to produce one more sets of encoded data slices,wherein the one or more sets of encoded data slices includes the one ormore encoded data slices; determining whether to establish a new accesspolicy corresponding to the one or more encoded data slices; when thenew access policy is to be established: determining a timestampregarding the new access policy; determining the new access policy,wherein the new access policy includes an access policy pattern; andsending the new access policy and the timestamp to one or more storageunits of the DSN that store the one or more encoded data slices; andwhen the new access policy is not to be established: determining one ormore slice names of one or more other encoded data slices.
 2. The methodof claim 1, wherein the one or more slice names include one of: aplurality of discrete and non-contiguous slice names, a contiguous rangeof slice names associated with a common data segment or a contiguousrange of slice names associated with a common data object.
 3. The methodof claim 1, wherein the determining one or more slice names is based onone or more of an access policy reconsideration request, where aprevious access policy update ended, a starting DSN address, a lookup, acommand, a request, a random number, a vault ID, a data object ID, or avirtual DSN address to a physical location table.
 4. The method of claim1, wherein the determining whether to establish the new access policy isbased on one or more of: an access policy reconsideration message, acurrent access policy for the one or more slice names, a command, a pasthistory of access policy reconsiderations, a history of slice accesssequences, a request, a predetermination, a data type, a securityindicator, a priority indicator, a DSN memory system status indicator, avault utilization indicator, or a DS managing unit message.
 5. Themethod of claim 1, wherein the determining the new access policy isbased on one or more of: an access policy reconsideration message, acurrent access policy for the one or more slice names, a command, a pasthistory of access policy reconsiderations, a history of slice accesssequences, a request, a predetermination, a data type, a securityindicator, a priority indicator, a DSN memory system status indicator, avault utilization indicator, or a DS managing unit message.
 6. Themethod of claim 1, wherein the determining the one or more slice namesand the determining whether to establish a new access policy are inresponse to receiving a reconsideration message that includes the one ormore slice names.
 7. The method of claim 6, further comprising:generating a reconsideration response message that indicates a denial ofreconsideration when the new access policy is not established.
 8. Aprocessing system of a dispersed storage network (DSN) comprises: atleast one processor; a memory that stores operational instructions, thatwhen executed by the at least one processor cause the processing systemto: determine one or more slice names of one or more encoded dataslices, wherein one or more data segments of data are dispersed storageerror encoded to produce one more sets of encoded data slices, whereinthe one or more sets of encoded data slices includes the one or moreencoded data slices; determine whether to establish a new access policycorresponding to the one or more encoded data slices; when the newaccess policy is to be established: determine a timestamp regarding thenew access policy; determine the new access policy, wherein the newaccess policy includes an access policy pattern; and send the new accesspolicy and the timestamp to one or more storage units of the DSN thatstore the one or more encoded data slices; and when the new accesspolicy is not to be established: determine one or more slice names ofone or more other encoded data slices.
 9. The processing system of claim8, wherein the one or more slice names include one of: a plurality ofdiscrete and non-contiguous slice names, a contiguous range of slicenames associated with a common data segment or a contiguous range ofslice names associated with a common data object.
 10. The processingsystem of claim 8, wherein the determining one or more slice names isbased on one or more of an access policy reconsideration request, wherea previous access policy update ended, a starting DSN address, a lookup,a command, a request, a random number, a vault ID, a data object ID, ora virtual DSN address to a physical location table.
 11. The processingsystem of claim 8, wherein the determining whether to establish the newaccess policy is based on one or more of: an access policyreconsideration message, a current access policy for the one or moreslice names, a command, a past history of access policyreconsiderations, a history of slice access sequences, a request, apredetermination, a data type, a security indicator, a priorityindicator, a DSN memory system status indicator, a vault utilizationindicator, or a DS managing unit message.
 12. The processing system ofclaim 8, wherein the determining the new access policy is based on oneor more of: an access policy reconsideration message, a current accesspolicy for the one or more slice names, a command, a past history ofaccess policy reconsiderations, a history of slice access sequences, arequest, a predetermination, a data type, a security indicator, apriority indicator, a DSN memory system status indicator, a vaultutilization indicator, or a DS managing unit message.
 13. The processingsystem of claim 8, wherein the determining the one or more slice namesand the determining whether to establish a new access policy are inresponse to receiving a reconsideration message that includes the one ormore slice names.
 14. The processing system of claim 13, wherein theoperational instructions, when executed by the at least one processor,further cause the processing system to: generate a reconsiderationresponse message that indicates a denial of reconsideration when the newaccess policy is not established.
 15. A non-transitory computer readablestorage medium comprises: at least one memory section that storesoperational instructions that, when executed by a processing system of adispersed storage network (DSN) that includes a processor and a memory,causes the processing system to: determine one or more slice names ofone or more encoded data slices; determine whether to establish a newaccess policy corresponding to the one or more encoded data slices; whenthe new access policy is to be established: determine a timestampregarding the new access policy; determine the new access policy,wherein the new access policy includes an access policy pattern; andsend the new access policy and the timestamp to one or more storageunits of the DSN that store the one or more encoded data slices; andwhen the new access policy is not to be established: determine one ormore slice names of one or more other encoded data slices.
 16. Thenon-transitory computer readable storage medium of claim 15, wherein theone or more slice names include one of: a plurality of discrete andnon-contiguous slice names, a contiguous range of slice names associatedwith a common data segment or a contiguous range of slice namesassociated with a common data object.
 17. The non-transitory computerreadable storage medium of claim 15, wherein the determining one or moreslice names is based on one or more of an access policy reconsiderationrequest, where a previous access policy update ended, a starting DSNaddress, a lookup, a command, a request, a random number, a vault ID, adata object ID, or a virtual DSN address to a physical location table.18. The non-transitory computer readable storage medium of claim 15,wherein the determining whether to establish the new access policy isbased on one or more of: an access policy reconsideration message, acurrent access policy for the one or more slice names, a command, a pasthistory of access policy reconsiderations, a history of slice accesssequences, a request, a predetermination, a data type, a securityindicator, a priority indicator, a DSN memory system status indicator, avault utilization indicator, or a DS managing unit message.
 19. Thenon-transitory computer readable storage medium of claim 15, wherein thedetermining the new access policy is based on one or more of: an accesspolicy reconsideration message, a current access policy for the one ormore slice names, a command, a past history of access policyreconsiderations, a history of slice access sequences, a request, apredetermination, a data type, a security indicator, a priorityindicator, a DSN memory system status indicator, a vault utilizationindicator, or a DS managing unit message.
 20. The non-transitorycomputer readable storage medium of claim 15, wherein the determiningthe one or more slice names and the determining whether to establish anew access policy are in response to receiving a reconsideration messagethat includes the one or more slice names.